The artificial sweetener commonly known as aspartame (APM) and identified as the methyl ester of L-aspartyl-L-phenylalanine, has become popular in recent years as a sweetener for chewing gum. However, the use of APM in particular chewing gum compositions which contain cinnamon flavor and/or other aldehyde-type flavors, has been characterized by a high degree of instability. Cinnamon flavor contains cinnamic aldehyde which reacts with APM, causing a loss in flavor and sweetness. Other aldehyde-type flavoring agents contain benzaldehyde, acetaldehyde, etc., which also react with APM. In addition to losing flavor and sweetness, chewing gums containing APM and aldehyde-based flavors can exhibit notable changes in texture, taste and color when stored for short periods of time.
Aspartame reacts chemically with aldehyde flavoring agents and particularly with cinnamic aldehyde. The reaction occurs to a significant extent in chewing gum, within a matter of days. This relatively rapid reaction has, in the past, rendered the use of APM impractical in gums containing cinnamon or other aldehyde-based flavoring agents. This problem is illustrated in FIG. 1, which compares APM stability in cinnamon flavored and unflavored gums.
Methods have been developed for the purpose of attempting to stabilize APM in a chewing gum environment. For instance, Glass et al. U.S. Pat. No. 4,822,621 discloses a technique in which the APM and the flavoring agent are initially blended into two separate gum portions, which are then coextruded together. Prior to chewing of the gum, the contact between the APM and the flavoring agent is generally limited to the interface between the coextruded portions.
Shoaf et al. U.S. Pat. Nos. 3,298,633 and 3,956,507, disclose a technique in which the APM is dispersed in a hot melt and the hot melt is cooled, thereby encapsulating the APM. Examples of hot melt ingredients include anhydrous and hydrous citric acid. Other fusing agents include monosaccharides, poly-saccharides and other materials. These references deal only with food and beverage applications.
Demaso et al. European Application 0 134 322 discloses that a low pH, preferably in the range of 2-3, is the most desirable for APM stability. The reference deals only with a process for incorporating APM into extruded food products including cereals and baked goods.
Klose et al. U.S. Pat. No. 4,246,286 discloses the stabilization of APM in a chewing gum composition, by adjusting the chewing gum pH to between 5.0 and 7.0. This is accomplished by eliminating calcium carbonate filler from the gum. Also, citric acid or another non-toxic organic acid is employed as a bulking agent.
Japanese Publication Sho 61-212255 discloses a sweetener composition containing APM, fructose and small amounts of organic acid and organic acid salts. The organic acid is selected from citric acid, tartaric acid, malic acid, fumaric acid and adipic acid.
Thus, it is known from the prior art that APM behaves in a more stable fashion in an acid environment. However, application of this knowledge to chewing gum compositions has been relatively limited until now.